The invention relates to a method of and apparatus for optimizing the clarified phase and the concentration of solids in a continuous solids-discharge centrifuge in which nozzles maintain the volume of concentrate to be extracted from the drum at a constant level and in which a photocell monitors the discharging clarified phase.
A method in which a photocell monitors the turbidity of the clarified phase, the liquid is fed into the centrifuge at a rate that depends on the turbidity, and a viscosimeter continuously determines the concentration of the concentrate discharge, some of which is returned to the centrifuge in accordance with the results of the determination, is known from U.S. Pat. No. 2,532,792 for example.
This system involves the drawbacks of automatic controls, which are at any rate expensive to install and operate. Determination of the viscosity of a concentration of solids discharged through nozzles is falsified by contact with the air during extraction. Furthermore, the on-off system necessary in automatic controls yields neither the maximum possible concentration of solids nor the lowest possible concentration of solids in the clarified phase.